New-Tech Europe Magazine | Dec 2017

making the capacitors short-circuit- proof. Compared with a battery, the supercaps only store about 10 Joules of energy, which generates no stress or significant heating effect on the part even under short-circuit conditions. Another feature of supercaps is the virtually unlimited number of charge and discharge cycles allowed compared with finite numbers for batteries. Lifetime is long, with temperature and applied voltage being accelerating factors. Under controlled conditions, however, the parts can easily give far more than five years of useful service. Any concern about moisture ingress is addressed by the laminate construction, with its minimal size of resin seal. Like electrolytics, the temperature range for supercaps is -40°C to +70°C or +85 °C with similar ESR variation at low temperatures. Supercaps are polarized and available up to about 5 V rating. In fact, the typical DMT and DMF series from Murata are already two ‘units’ in series. Higher voltages can be easily achieved with series connection of the parts, with passive or active voltage balancing schemes. Paralleling is also easy with no special precautions necessary to achieve more energy storage. Charging is as quick as an electrolytic capacitor from a simple voltage source. A significant benefit is the ultra-slim form factor of the Murata DMT and DMF series down to just 2.2 mm matching the demands of today’s ‘pocketable’ and wearable electronics. Moving forward, portable devices will become more multi-functional, smaller and lighter. Supercapacitors from Murata represent a complementary and enabling technology.

Figure 1. Power comparison of Murata’s supercapacitors with various battery technologies

Figure 2. Supercapacitor packages

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